Since both bikes are 800's everyone i comparing them but they are actually going after different niches. The Triumph is best thought of as a smaller adventure touring 1150GS or 1200 GS. An adventure touring machine while the BMW is best thought of a larger BMW Xchallenge also a adventure touring but one foot in the enduro camp. Better on the single track while the triumph excells on the dirt roads and pavement. The F800GS is better for those guys that want a weekend thrasher and the triumph is better for longer trips. Your not going to use the 1150GS as a weekend thrasher and you won't use the Triumph for that either. Of course folks can and due use the BMW for long adventure trips. Its going to do great because its a good bike but after several days you'd probably more appreciate the Tiger. Of course you could use the Tiger on single track but thats not what it was made for and why tear up such a pretty machine?
It says something about both bikes when on rag says the Tiger is a better bike while another picks the F800GS as a better bike. Generalities are not always good thought tools to use but to understand each niche think of the Tiger as a light more nimble 1200GS. The BMW F800GS is not a smaller 1200GS you know this to be true. Its something else its got more enduro DNA than the other GS's.
Now lets see if the lost sticker guy spazes out again :(